Semiconductor Pad Array Segmentation for Stress and Reliability
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Solution Overview
Problem
Conventional semiconductor device pads formed using different methods exhibit varying reliability issues, such as reduced adhesion, poor mechanical performance, stress concentration, and poor reliability in temperature cycling, leading to overall low reliability and functional performance.
Innovation Solution
The semiconductor device incorporates a combination of via-in-pad (VIP) and non-via-in-pad (NVIP) pads, where VIP pads directly contact conductive vias and NVIP pads are isolated from vias, arranged in fine pitch regions and high-stress areas respectively, to enhance package density and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pads are formed using conventional methods, then manufacturing is simpler, but reliability under stress and temperature cycling is poor
Solution Approach 1:
The pad array is segmented into two distinct types: VIP pads with underlying conductors and NVIP pads without underlying conductors. This segmentation allows each pad type to be optimized for specific functions - VIP pads for electrical connectivity and NVIP pads for stress distribution - thereby improving overall reliability while managing complexity through functional differentiation.
Solution Approach 2:
Different pad configurations are applied to different locations within the pad array. VIP pads are strategically placed where electrical connectivity is required, while NVIP pads are positioned in areas benefiting from stress distribution. This local quality approach ensures that each region of the substrate receives the appropriate pad type for its specific functional requirements, optimizing both reliability and performance.
2Reliability
If VIP pads are used to improve electrical connectivity, then conductivity is enhanced, but stress concentration increases
Solution Approach 1:
The pad array is segmented into two distinct types: VIP pads with underlying conductors and NVIP pads without underlying conductors. This segmentation allows each pad type to be optimized for specific functions - VIP pads for electrical connectivity and NVIP pads for stress distribution - thereby improving overall reliability while managing complexity through functional differentiation.
Solution Approach 2:
Different pad configurations are applied to different locations within the pad array. VIP pads are strategically placed where electrical connectivity is required, while NVIP pads are positioned in areas benefiting from stress distribution. This local quality approach ensures that each region of the substrate receives the appropriate pad type for its specific functional requirements, optimizing both reliability and performance.
3Strength
If NVIP pads are used to reduce stress concentration, then mechanical performance improves, but electrical connectivity is reduced
Solution Approach 1:
The pad array is segmented into two distinct types: VIP pads with underlying conductors and NVIP pads without underlying conductors. This segmentation allows each pad type to be optimized for specific functions - VIP pads for electrical connectivity and NVIP pads for stress distribution - thereby improving overall reliability while managing complexity through functional differentiation.
Solution Approach 2:
Different pad configurations are applied to different locations within the pad array. VIP pads are strategically placed where electrical connectivity is required, while NVIP pads are positioned in areas benefiting from stress distribution. This local quality approach ensures that each region of the substrate receives the appropriate pad type for its specific functional requirements, optimizing both reliability and performance.
4Quantity of substance
If pad density is increased to improve package density, then package size is reduced, but reliability under drop test decreases
Solution Approach 1:
The pad array is segmented into two distinct types: VIP pads with underlying conductors and NVIP pads without underlying conductors. This segmentation allows each pad type to be optimized for specific functions - VIP pads for electrical connectivity and NVIP pads for stress distribution - thereby improving overall reliability while managing complexity through functional differentiation.
Solution Approach 2:
Different pad configurations are applied to different locations within the pad array. VIP pads are strategically placed where electrical connectivity is required, while NVIP pads are positioned in areas benefiting from stress distribution. This local quality approach ensures that each region of the substrate receives the appropriate pad type for its specific functional requirements, optimizing both reliability and performance.
Data Source
AI summary
A semiconductor device includes a first substrate, a pad array, a conductive bump, a first via and a dielectric. The pad array, formed on a surface of the first substrate, includes a first type pad and a second type pad at a same level. The conductive bump connects one of the first type pad of the second type pad to a second substrate. The first via, connected to a conductive feature at a different level to the first type pad, is located within a projection area of the first type pad and directly contacts the first type pad. The second type pad is laterally connected with a conductive trace on the same level. The conductive trace is connected to a second via at a same level with the first via. The dielectric in the first substrate contacts the second type pad. The second type pad is floated on the dielectric.